The present invention relates to control systems for model trains.
Model train systems have been in existence for many years. In the typical system, the model train engine is an electrical engine which receives power from a voltage which is applied to the tracks and picked up by the train motor. A transformer is used to apply the power to the tracks. The transformer controls both the amplitude and polarity of the voltage, thereby controlling the speed and direction of the train. In HO systems, the voltage is a DC voltage. In Lionel systems, the voltage is an AC voltage transformed from the 60 Hz line voltage available in a standard wall socket.
In addition to controlling the direction and speed of a train, model train enthusiasts have a desire to control other features of the train, such as a whistle. Lionel allows for such control of the whistle by imposing a DC voltage on top of the AC line voltage, which is then picked up by the locomotive. Obviously, this method is limited in the number of controls that can be transmitted, since there are only plus and minus DC levels available, along with varying amplitudes. One method for increasing the number of control signals available by use of a state machine in the locomotive is disclosed in Severson, U.S. Pat. No. 4,914,431.
Another type of control system is shown in Hanschke et al., U.S. Pat. No. 4,572,996. This patent teaches sending address and control signals over a rail line bus to a train. The signals sent appear to be digital pulses. In Kacerek, U.S. Pat. No. 3,964,701, each train locomotive will respond to a different frequency signal. After the corresponding frequency signal is sent to alert the train, it is followed by a voltage level indicating the action to be taken.
Marklin makes a system which puts high power signals differentially between the tracks. These signals are used to provide power to the train's motor as well as for signalling control signals. Other systems use RF transmissions directly to the trains through the air. Still other systems will superimpose a high frequency signal on the track power signal that is applied differentially between the tracks. One problem with such systems is the intermittent contact between the wheels and the track, the noise generated by the brush motors used and intermittent contact due to gaps in the track. The RF transmitters which transmit directly to the trains have the disadvantage of requiring a large antenna, cost and complexity.